‫جامعة تكريت‬
‫كلية طب االسنان‬
‫مادة طب اجملتمع‬
‫املرحلة الثالثة‬
‫م‪ .‬ازهار عماش حسني‬
‫‪6102-6102‬‬
‫‪1‬‬
Dental Indices
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Epidemiological methods of the study require the conditions be
measured and quantified accurately based on sound scientific principles.
One of the major problem in studying dental diseases and its factors is the
development of a suitable, practicable method for recording the
occurrence and severity of disease. Quantitative measurement of disease
most commonly relies on “index”. So, dental index is the main tool of
epidemiological studies in dental diseases to measure incidence,
prevalence and severity.
Index
A numerical value describing the relative status of a population on a
graduated scale with definite upper and lower limits, which is designed to
permit and facilitate comparison with other populations classified by the
same criteria and methods.
Objectives
1. To increase understanding of the disease process, leading to
methods of control and prevention.
2. To discover populations at high and low risk.
3. To define the specific problem under investigation.
Ideal properties of an index
1- Clarity, simplicity, and objectivity:
- The examiner should be able to carry the rules of the index in his mind.
- The index should be easily to apply, so there is no undue time lost
during examination.
- The index criteria should be clear and unambiguous.
2- Validity:
The index should be measure what it is intended to measure, so it should
be correspond with clinical stages of the disease, ex: numbers of missing
teeth in adults are not a valid measure of caries activity.
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3- Reliability:
The index should measure consistently at different times and under a
variety of conditions. Reproducibility: the ability of the same or different
person to use the index in the same way.
4- Quanti fiability:
The index should be a mean able to statistical analysis. The status of a
group can be expressed by a number that corresponds to a relative
position on a scale from zero to the upper limit.
5- Sensitivity:
The index should be able to detect reasonably small shift, in either
direction in the group condition.
6- Acceptability:
The use of the index should not be painful or demeaning to the subject.
Uses of dental indices
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To study oral health status of individuals and population.
To study prevalence and incidence of diseases.
To provide data for epidemiological studies.
For planning of oral health policy.
To evaluate the effectiveness of oral health programs.
To provide data for research to find out etiological and
predisposing factors for the diseases.
7- To evaluate the success of various preventive programs.
8- To compare oral health status of individuals and population.
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Classification of indices
Based upon the:
A-Direction in which their scores can fluctuate:
1- Irreversible index
ex: DMF
Index that measures conditions will not return to the normal state.
Once establish cannot decrease in value on subsequent
examinations.
2- Reversible index
ex: GI
Index that measure conditions that can be return to the normal
state. Reversible index scores can decrease or increase in value on
subsequent examinations.
3- Composite index
ex: Russell’s PI
Index that measure conditions that can be return to the normal state
and conditions will not retain to the normal state.
B- The extent to which areas of oral cavity are measured:
1- Full mouth index
ex: Russell’s PI
These indices measure the patient’s entire periodontium or dentition.
2- Simplified index
ex: OHI-S
These indices measure only a representative sample of the dental
apparatus.
C- The entity which they measure:
1- Disease index
D MF
2- Treatment index DM F
3- Symptom index PBI
D- The special categories:
1- Simple index
PlI
Index that measure the presence or absence of condition.
2- Cumulative index DMF
Index that measure all the evidence of a condition, past and
present.
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Scale
1- Ordinal scale: it is a scale of measurement that list conditions in
some order of severity without attending to define mathematical
relation between the categories.
GI
0
no inflammation
1
mild
2
moderate
3
severe
2- Nominal scale: a scale that gives name to different condition.
OHI
good poor
fair
3- Interval or ratio: a scale that uses number in measuring and has
mathematical relation to each other.
In ratio scale there is a true zero, GI 0=no inflammation.
In interval scale there is no true zero.
A numerical value describing the relative status of a population on a
graduated scale with definite upper and lower limits, which is designed to
permit and facilitate comparison with other populations classified by the
same criteria and methods.
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